The present invention relates to combine harvester unloader tube pivot mechanisms.
It is known to provide agricultural vehicles such as combines with a container for temporarily storing grain that the combine has harvested and threshed. Operatively connected with these containers are unloading tubes through which the grain from the container passes during grain unloading operations. An auger is typically positioned within the unloading tube for directing grain from the container into and through the unloading tube. As grain is unloaded from the combine""s grain container through the unloading tube in this manner the grain is expelled into a truck or grain cart traveling next to the combine.
Many conventional unloading tubes include a generally upright lower portion operatively connected with and extending upwardly from a lower portion of the combine grain container. A generally horizontally extending portion of the unloader tube is operatively coupled with the upper end portion of the upright portion. Augers are typically positioned within the upright portion and horizontally extending portions of the unloader tube. A gearbox is often provided at the junction of the upright and horizontal portions of the unloader tube for operatively connecting the auger sections in the two portions of the unloader tube.
Conventional unloader tubes are adapted to pivot between two positions about the central axis of the upright portion of the tube. In a first position the horizontal portion of the unloader tube is positioned generally longitudinally with respect to the vehicle and is located in close proximity along the side of the vehicle. The unloader tube can be swung outwardly from this position about the central axis of the upright portion to a position whereat the horizontal portion of the tube extends generally laterally outwardly from the side of the combine. The outer end of the unloader tube is positioned relatively high in the air such that a grain truck or cart can be positioned under the end of the tube to receive the grain being propelled from the tube.
The unloader tubes tend to be relatively heavy structures, since they house the augers and bear a large amount of weight when they carry heavy amounts of grain during operation. The unloader tubes must therefore be braced to withstand these forces during operation. Conventional combines typically include an upper support structure above the tube""s upright portion. The upper support mechanism helps keep the upright portion of the tube securely in place as it pivots and helps keep the upright portion from toppling over due to the weight of the tube, augers and grain within the tube. The upright portion of the unloader tubes are held firmly in position by a sturdy support ring structure that supports the lower portion of the tube and allows the unloader tube to pivot.
Conventional support ring structures typically include male and female cast ring members that form part of the unloader tube. The male cast ring is positioned below and is received by the female cast ring. The male and female cast rings bear against each other and pivot in contact with each other as the unloader tube is swung to its various positions. The female cast ring typically includes a means for lubricating the surfaces of the male and female cast rings that bear against each other. Conventional grease fittings and grease channels are provided for allowing grease to be applied to the bearing surfaces. Grain, dust and other small particles travelling upwardly in the unloader tube often become lodged in the grease channels and between the bearing surfaces. Such contaminants can wear down the male and female cast rings as the two parts pivot with respect to each other. The contaminants can also clog the lubrication system such that the bearing surfaces become dry and wear due to lack of lubrication. Therefore operators of such systems must frequently check and maintain the lubrication system to prevent excessive wear.
It would therefore be desirable to provide a mechanism that allows an unloader tube to pivot to its various positions, and which is not prone to wear due to contaminants. It would be desirable to provide a mechanism that does not require an operator to regularly check and maintain a lubrication system. It would be desirable to provide a mechanism that does not require lubrication, and therefore eliminates the need for a lubrication system.
The present invention provides a combine unloader tube pivot mechanism that includes upper and lower unloader tube portions positioned closely adjacent each other and which pivot with respect to each other to allow the unloader tube to pivot. Upper and lower ring-shaped pivot ring bushings are fixed for pivotal motion with respective upper and lower unloader tube portions. The upper and lower pivot bushings provide bearing surfaces through which weight from the upper unloader tube portion is transmitted to the lower unloader tube portion. The upper and lower pivot bushings are slidable in contact with each other as the unloader tube pivots to its various positions. The upper and lower pivot bushings are made of an ultra high molecular weight material. Mating shapes are formed in the upper and lower pivot bushings and the upper and lower unloader tube portions. These mating shapes block the upper and lower pivot bushings from pivoting with respect to the respective upper and lower unloader tube portions. The mating shapes according to the preferred embodiment include peg members formed in the pivot bushings and openings formed in the upper and lower unloader tube portions for receiving the peg members.